The present invention relates to a safety harness and, more particularly, to a safety harness to be worn by a person to protect that person from injury in case of a fall.
Safety harnesses are commonly used as part of a fall protection system for persons subjected to the potential of a fall from a height. In the workplace, full-body safety harnesses are generally used. Such harnesses, which typically include both an upper torso portion (having, for example, shoulder straps) and a lower torso portion (having, for example seat straps and leg straps), can be designed in many alternative manners.
Most currently available full-body safety harnesses are manufactured from relatively inelastic, woven webbing materials such as nylon or polyester. A portion of a harness strap 1 including such a webbing material 2 is illustrated in FIGS. 1A through 1C. Although the strength of such materials is well suited for fall protection, harnesses fabricated from such materials cause discomfort for the user by, for example, impairing movement of the worker and digging into the worker""s body at the lateral edges of the straps. In that regard, inelastic webbing material 2 limits the range of motion of the user and has relatively thin, sharp lateral edges 3 and 5 that displace the user""s skin and dig into the user""s body when under even relatively low tension forces experienced in normal use of a safety harness. The resultant discomfort, reduces effectiveness of the worker and causes relatively quick fatigue. The limited range of motion, discomfort and fatigue associated with current safety harnesses can result in safety lapses by the worker.
Recently, a flexible and elastic harness, as described in U.S. Pat. No. 6,006,700, the disclosure of which is incorporated herein by reference, has been introduced that greatly improves the comfort of the user.
Nonetheless, it remains desirable to develop safety harnesses resulting in improved user comfort and improved overall safety.
The present invention provides a safety harness to be worn by a person including a strap portion for extending over a portion of the person""s body to retain the person within the safety harness. The lateral edges of the strap portion preferably remain, for example, relatively thick as well as blunted, arced or rounded rather than forming a thin or sharp edge in contact with the user""s body when the strap portion is under tension forces experienced in normal use of the safety harness (that is, use of the safety harness in situations other than a fall). In that regard, the lateral edges of the strap portion in contact with the user""s body preferably remain relatively thick as well as blunted, arced or rounded under tension forces of up to approximately 100 pound. More preferably, the lateral edges of the strap portion remain relatively thick as well as blunted, arced or rounded under tension forces of up to approximately 150 pounds. Most preferably, the lateral edges of the strap portion remain relatively thick as well as blunted, arced or rounded under tension forces of up to approximately 200 pounds.
The relatively thick, arced, rounded or blunted lateral edges of the strap portion of the present invention do not xe2x80x9cdig intoxe2x80x9d the body of the user during use of the safety harness and reduce or eliminate the binding, pinching and chaffing common with the relatively thin, xe2x80x9csharpxe2x80x9d lateral edges of currently available safety harnesses.
In one embodiment of a safety harness of the present invention, at least a section of the strap portion includes an outer shell of a high strength, flexible material. The outer shell has a channel therein. The outer shell can, for example, have a tubular construction. The strap portion further includes a flexible inner member within the channel of the outer shell. The flexible inner member generally prevents the lateral edges of the strap portion from forming a thin, sharp edge (as discussed above) when under tension.
The flexibility of the inner member is preferably limited such that the inner member retains its shape sufficiently to prevent tangling of the strap portion when not in use.
In one embodiment, the inner member is elastic and the length of the tubular outer shell is sufficiently long to allow extension of the strap portion. The outer shell preferably has an ultimate tensile of at least 4000 pounds. In another embodiment, the inner member is elastic and the outer member is fabricated from a high strength, elastic material. In that embodiment, the material of the outer shell preferably has an ultimate tensile of at least 4000 pounds and exhibits an elastic extension of at least approximately 3% under a tensile load of approximately 20 pounds. As appreciated by one skilled in the art, however, neither the inner member or the outer shell is required to be elastic.
The inner member is preferably adapted to maintain the thickness of the strap portion of the present invention (particularly in the region of the lateral edges thereof) in a range of approximately 0.25 inches to 0.5 inches. To further improve comfort of the safety harness of the present invention, the inner member is preferably compressible, yet maintains the thickness of the strap portion in the range discussed above. In that regard, the inner member preferably exhibits a compression of approximately 25% at an applied pressure in the range of approximately 4 to approximately 10 lb/in2. The inner member also preferably exhibits a compression of approximately 50% at an applied pressure in the range of approximately 8 to approximately 20 lb/in2.
A minimum stiffness for the material of the inner member can be defined such that the inner member deflects no more than approximately 0.75 inches when extended over an edge to a distance of approximately 1 inch past the edge and placed under a load of approximately 2 ounces. A maximum stiffness for the material of the inner member can be defined such that the inner member deflects no more than approximately 0.75 inches when extended over an edge to a distance of approximately 4 inch past the edge and placed under a load of approximately 2 ounces.
The present invention also provided a safety harness to be worn by a person including a strap portion for extending over a portion of the person""s body to retain the person within the safety harness. At least a section of the strap portion includes an outer shell of a high strength, flexible material and a flexible inner member. The flexibility of the inner member is preferably such that the inner member does not substantially interfere with motion of the person when the safety harness is in use but that the strap portion generally retains its shape when the safety harness is not in use.
The present invention also provides a method of manufacturing a strap for a safety harness for extending over a portion of the person""s body to retain the person within the safety harness. The method preferably includes the steps of providing an outer shell of high strength, flexible material having an inner channel, and placing a flexible inner member within the inner channel of an outer shell of the high strength, flexible material. The flexible inner member generally prevents the lateral edges of the strap portion from forming a thin, sharp edge when under tension as discussed above. As also discussed above, the flexibility of the inner member is preferably such that the inner member does not substantially interfere with motion of the person when the safety harness is in use but that the strap portion generally retains its shape when the safety harness is not in use.